Does a concept, such as the Law of Gravity, exist? If there was no such thing as mass or time, would the Law still exist - just in case?

Take a law-statement of the form "All As are Bs" (I'm not saying that every law-statement has to be of this form: but it will do no harm to concentrate on this type of case). Then we can ask a pair of related questions. First, what kind of fact(s) make this type of law-statement true? For if the statement isn't even true, it certainly isn't a law. And we can ask, second, what makes the statement a law-statement. For not all true generalizations are laws: some are just accidentally true.

Different philosophers offer different package answers to this pair of questions, and the issues here are very hotly contended. It would be difficult to say much about them here, and we'll have to shelve any extended discussion. But let's see if we can make just a few preliminary comments relevant to the question originally posed.

First: note that sometimes when people talk about laws they mean law-statements; sometimes when people talk about laws they mean the facts that make the law-statements true (facts that existed/will continue to exist independently of our ever stumbling across them and putting them into words). Now, talking of laws as "concepts" strongly suggests the first understanding of "law" -- though strictly speaking law-statements involve concepts as ingredients, but are not themselves properly described as concepts. On the other hand, talking of laws as "existing" strongly suggests the second understanding of "law", and raises issues about the existence of law-facts. So the way the original question is framed is perhaps in danger of confusing the two senses of "law".

Second, however, it certainly seems that it sometimes could be a law that all As are Bs even though there happen to be no As. Newton's First Law says that any object subject to zero net forces will move in a straight line with constant velocity. What if the world happens not to contain any object which is subject to zero net forces? Would we want to say on this ground that Newton got it wrong, and that there is no such law-fact? Arguably not. In this sort of case, the non-existence of As wouldn't seem to imply the non-existence of laws about As.

But that's not the end of the story. It was once believed, for example, that the statement "combusting materials give off phlogiston" was a law. It isn't, because it is false. There is no such stuff as phlogiston. And since there is no such stuff, we are rather inclined to say, there can't be any genuine laws about it either. In this sort of case, the non-existence of As does seem to imply the non-existence of laws about As.

What makes the difference between these cases? Now, that's a good question. But I suspect that taking it very much further would mean having to tackle head-on the tricky big issues that we shelved! (You can perhaps at least get a sense of the complexity of those issues by looking here.)

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